Page 130 - Principles of Applied Reservoir Simulation 2E

Part II: Reservoir Simulation 115

12.3 Reservoir Description Using Seismic Data

Reservoir geophysics has the potential to image important reservoir
parameters in regions between wells. This potential has limitations, but before
discussing these limitations, let us first consider how reservoir geophysics may
be used and review an example where the potential of reservoir geophysics was
realized.
The reservoir geophysical procedure requires the correlation of seismic
data with reservoir properties. Correlations are sought by making crossplots of
seismic data with reservoir properties. Some correlation pairs are listed below.
4 Seismic Amplitude vs Rock Quality
0 Rock Quality = kh net, $kh net, etc.
^ Seismic Amplitude vs Oil Productive Capacity (OPC)

4 Acoustic Impedance vs Porosity
If a statistically significant correlation is found, it can be used to guide the dis-
tribution of reservoir properties between wells. Ideally, the property distribution
procedure will preserve reservoir properties at wells.
De Buyl, et al. [ 1 988] used reservoir geophysics to predict reservoir pro-
perties of two wells. They correlated well-log-derived properties with seismically
controlled properties, for example, porosity, then used the correlation to
distribute properties. Maps drawn from seismically controlled distributions
exhibited more heterogeneity than conventional maps drawn from well-log-
derived properties. Unlike geostatistics, where additional heterogeneity is
obtained by sampling from a probability distribution, heterogeneity based on
seismically controlled distributions represents spatial variations in reservoir
properties determined by direct observation, albeit observation based on
interpreted seismic data.
An indication of the technical success of the reservoir geophysical
technique is given in Table 12-4. Actual values of reservoir parameters at two
well locations are compared with values predicted using both well-log-derived
properties and seismically controlled properties. This work by De Buyl, et al.
[1988] is notable because it scientifically tests the seismic method: it makes